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FEATURES
Superior Upgrade for MAX696/MAX697
Specified Over Temperature
Adjustable Low Line Voltage Monitor
Power OK/Reset Time Delay
Reset Assertion Down to 1 V V
CC
Watchdog Timer—100 ms, 1.6 s, or Adjustable
Low Switch On Resistance
1.5 Normal, 20 in Backup
600 nA Standby Current
Automatic Battery Backup Switching (ADM696)
Fast On-Board Gating of Chip Enable Signals (ADM697)
Voltage Monitor for Power Fail or Low Battery Warning
APPLICATIONS
Microprocessor Systems
Computers
Controllers
Intelligent Instruments
Automotive Systems
Critical P Power Monitoring
V
BATT
Microprocessor
Supervisory Circuits
ADM696/ADM697
FUNCTIONAL BLOCK DIAGRAMS
BATT ON
V
OUT
V
CC
LL
IN
LOW LINE
RESET
RESET GENERATOR
RESET
OSC IN
OSC SEL
TIMEBASE FOR RESET
AND WATCHDOG
WATCHDOG
TIMER
WATCHDOG
TRANSITION DETECTOR
WATCHDOG
OUTPUT (WDO)
WATCHDOG
INPUT (WDI)
POWER FAIL
INPUT (PFI)
1.3V
ADM696
POWER FAIL
OUTPUT (PFO)
GENERAL DESCRIPTION
The ADM696/ADM697 supervisory circuits offer complete
single chip solutions for power supply monitoring and battery
control functions in microprocessor systems. These functions
include
µP
reset, backup-battery switchover, watchdog timer,
CMOS RAM write protection, and power failure warning.
The ADM696/ADM697 are available in 16-pin DIP and small
outline packages and provide the following functions:
1. Power-On Reset output during power-up, power-down and
brownout conditions. The RESET voltage threshold is
adjustable using an external voltage divider. The
RESET
output remains operational with V
CC
as low as 1 V.
2. A Reset pulse if the optional watchdog timer has not been
toggled within specified time.
3. Separate watchdog time-out and low line status outputs.
4. Adjustable reset and watchdog timeout periods.
5. A 1.3 V threshold detector for power fail warning, low bat-
tery detection, or to monitor a power supply other than V
CC
.
6. Battery backup switching for CMOS RAM, CMOS micro-
processor or other low power logic (ADM696).
7. Write protection of CMOS RAM or EEPROM (ADM697).
CE
IN
LL
IN
CE
OUT
LOW LINE
RESET
RESET GENERATOR
RESET
OSC IN
OSC SEL
TIMEBASE FOR RESET
AND WATCHDOG
WATCHDOG
TIMER
WATCHDOG
TRANSITION DETECTOR
WATCHDOG
OUTPUT (WDO)
WATCHDOG
INPUT (WDI)
POWER FAIL
INPUT (PFI)
1.3V
ADM697
POWER FAIL
OUTPUT (PFO)
The ADM696/ADM697 is fabricated using an advanced epitaxial
CMOS process combining low power consumption (5 mW),
extremely fast Chip Enable gating (5 ns) and high reliability.
RESET
assertion is guaranteed with V
CC
as low as 1 V. In
addition, the power switching circuitry is designed for minimal
voltage drop thereby permitting increased output current drive
of up to 100 mA without the need for an external pass transistor.
REV. 0
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 617/329-4700
Fax: 617/326-8703
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